should only effect x86 when using long double.  Now
12/16 bytes are output for long double globals (the
exact amount depends on the alignment).  This brings
globals in line with the rest of LLVM: the space
reserved for an object is now always the ABI size.
One tricky point is that only 10 bytes should be
output for long double if it is a field in a packed
struct, which is the reason for the additional
argument to EmitGlobalConstant.

llvm-svn: 43688